# A question on Elementary Set Theory

In a recent survey of $400$ students in a college, $100$ were listed as studying typing and $150$ were listed as doing accountancy.

a. Find the number of students in the college who are not registered for either course?

b. How many students were registered for typing only?

Illustrate the results with a Venn diagram.

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–  wj32 Oct 24 '12 at 6:11
Hello welcome to MSE. Would you please show your attempts at this question to let us see what you might need? –  FrenzY DT. Oct 24 '12 at 6:12
This question has a short, simple answer: the information given is not sufficient to answer the question. One can illustrate this by giving multiple solutions consistent with the problem statement. Closing it as not constructive is absurd. Closing it as not a real question would have been defensible, if in my view unnecessarily harsh. –  Brian M. Scott Oct 24 '12 at 17:09
There is now a meta question about the closure of this question. –  Bill Dubuque Oct 24 '12 at 18:39
Like your first question, this one has no definite answer, because it doesn’t contain enough information. From what we’re told, it’s possible that all of the students who were taking typing were also taking accountancy; in that case there would be $400-150=250$ students not registered for either course, and no students registered for typing only. At the other extreme it’s possible that no student is taking both typing and accountancy; in that case there are $$400-(100+150)=400-250=150$$ students who are not registered for either course, and $100$ who are registered for typing only.